1. Field of the Invention
The present invention relates generally to medical methods and apparatus. More particularly, the present invention relates to methods and apparatus for sealing collateral passages between adjacent lung segments prior to endobronchial lung volume reduction.
Chronic obstructive pulmonary disease is a significant medical problem affecting 16 million people or about 6% of the U.S. population. Specific diseases in this group include chronic bronchitis, asthmatic bronchitis, and emphysema. While a number of therapeutic interventions are used and have been proposed, none are completely effective, and chronic obstructive pulmonary disease remains the fourth most common cause of death in the United States. Thus, improved and alternative treatments and therapies would be of significant benefit.
Of particular interest to the present invention, lung function in patients suffering from some forms of chronic obstructive pulmonary disease can be improved by reducing the effective lung volume, typically by resecting diseased portions of the lung. Resection of diseased portions of the lungs both promotes expansion of the non-diseased regions of the lung and decreases the portion of inhaled air which goes into the lungs but is unable to transfer oxygen to the blood. Lung volume reduction is conventionally performed in open chest or thoracoscopic procedures where the lung is resected, typically using stapling devices having integral cutting blades.
While effective in many cases, conventional lung volume reduction surgery is significantly traumatic to the patient, even when thoracoscopic procedures are employed. Such procedures often result in the unintentional removal of healthy lung tissue, and frequently leave perforations or other discontinuities in the lung which result in air leakage from the remaining lung. Even technically successful procedures can cause respiratory failure, pneumonia, and death. In addition, many older or compromised patients are not able to be candidates for these procedures.
As an improvement over open surgical and minimally invasive lung volume reduction procedures, endobronchial lung volume reduction procedures have been proposed. Such endobronchial lung volume reduction procedures involve the isolation, typically permanent, of one or more diseased lung segments in order to reduce the effective lung volume and increase the portion of inhaled air which is absorbed into the blood through the lungs. Minimally invasive lung volume reduction procedures typically use a catheter which is introduced through the trachea into the branching airways of the lung. A valve plug, such as an or occlusal stent, is then implanted in an airway which feeds the diseased lung segment(s). Often, more than one such blocking element can be placed at airways feeding multiple diseased lung segments. In some instances, the isolated lung segments can be aspirated or passively deflated in order to enhance closure of the diseased region. In other cases, oxygen-rich gases may be introduced in order to induce oxygen atelectasis to still further induce collapse and closure of the diseased region.
Although such minimally invasive lung volume reduction procedures have been very effective in some patients, they have been less effective in other patients where the diseased lung segments are open to adjacent healthy or diseased segments through collateral flow channels. Normally, lung segments are defined and circumscribed by a fibrous septum (wall) which prevents the flow of air or other gases from one segment into adjacent segments. In diseased patients, the walls between adjacent lung segments may be damaged and form the collateral flow channels which permit reentry of air or other gases into the “isolated” segment being treated.
For these reasons, it would be desirable to provide methods for sealing such collateral flow channels between adjacent lung segments. Such sealing methods would be particularly useful for treating patients prior to endobronchial or other lung volume reduction procedures. Thus, methods and apparatus for sealing collateral flow channels should be compatible with known protocols for occluding diseased lung segments and regions for performing lung volume reduction, including the placement of plugs and occluding members within the airways leading to such diseased lung segments and regions. At least some of these objectives will be met by the inventions described hereinbelow.
2. Description of the Background Art
Methods for performing minimally invasive and endobronchial lung volume reduction are described in the following patents and publications: U.S. Pat. Nos. 5,972,026; 6,083,255; 6,258,100; 6,287,290; 6,398,775; 6,527,761; 6,585,639; 6,679,264; 6,709,401; 6,878,141; 6,997,918; 2001/0051899; and 2004/0016435.